Some materials, such as cells, tissue or other biological materials, require very low temperatures and these materials are often cryogenically preserved with liquid nitrogen at about −196 degrees Celsius for storage and transportation. Maintaining such low temperatures with liquid nitrogen is often handled in one of two ways.
One method including liquid nitrogen cooled materials involves the use of a hermetically sealed container. Since cryogenic fluids, such as liquid nitrogen, transition from a liquid phase to a gas phase during transport, a hermetically sealed container requires a system to control the initial pressure of the interior of the container. Otherwise, pressure builds as the liquid nitrogen expands during this transition. For this reason, hermetically sealed containers can be expensive and bulky, and the required system for controlling the initial pressure can also result in increased costs. Such hermetically sealed containers can only be constructed from bulky materials such as metal, which contributes to an overall weight too great for use as a personal portable container. Due to the brittle nature of glass, it may not be suitable for such hermetically sealed containers because glass may explode as pressure builds within the container.
A second method for transporting liquid nitrogen cooled materials involves the use of a non-hermetically sealed container. Such containers allow nitrogen vapors to escape. These containers should remain upright in order to avoid leakage or spilling of the liquid nitrogen. Often non-hermetically sealed, large metal containers, or cryostats, are used for the transport cryopreserved materials. These containers typically comprise double walled metal containers that have a first wall separated from a second inner wall which holds the liquid nitrogen. The cryostats weight alone contributes significantly to the cost of shipping. Additionally, the long cylindrical shapes of typical cryostats can often put them at risk for tipping during shipment. Such canisters also require complicated valves and lids with pressure release mechanisms, which can significantly increase the cost of producing a non-hermetically sealed container. This can be particularly problematic for cryogenic containers which are only intended for a single use, or for a very limited number of uses.
Regardless of whether the container is hermetically sealed or not, most previous containers for cryopreserved materials were constructed from bulky and heavy metals and lacked the portability. Such containers could require dollies or other mechanical advantages for transport.
Some dry shippers may be lighter containers that include liquid nitrogen absorbing material for the shipment of cryopreserved materials. The liquid nitrogen absorbing material may retain liquid nitrogen for cooling, while reducing or eliminating free flowing liquid nitrogen within the container. Such containers may accommodate suspending a first vessel within a container and may fail to provide a compact and secure cryocontainer suitable for an individual to carry.